I wrapped up installation and testing of a simple BASIC Stamp 2 watchdog board for Zaza's ACCESS.bus MSP network yesterday. The board has the ability to detect when the ACCESS.bus is hung, and and can assert the MSP reset line when directed to do so by the 'brain' CPU (zaza1). I have begun work on a new version of the MSP supervisor utility to take advantage of the enhanced functionality that the new board provides. When completed, the utility will allow fail-safe starts from power up, eliminating the need to press the ACCESS.bus reset switch, as well as detecting bus problems during normal operation. I had considered adding code to support bus monitoring to the baseServer, but this might break things, and make porting the codebase to CARMEN more difficult. Bus monitoring will be implimented via an external supervisor utility that links with libmsp. This will allow passive bus monitoring to occur regardless of whether baseServer is running.
The schematics (gEDA/gschem + additional custom symbols, PNG) and current firmware are here.